Dishwashing machine and porous pad



Jan. 9, 1968 H. C. WILLIAMSON DISHWASHING MACHINE AND POROUS PAD Filed Dec. 17, 1965 FIGS.

WITNESSES INVENTOR Hugh C. WiHiomson United States Patent 3,362,139 DISHWASHING MACHINE AND POROUS PAD Hugh C. Williamson, Columbus, Ohio, assignor to Westinghouse Electric Corporation, Pittsburgh, Pa., a corporation of Pennsylvania Filed Dec. 17, 1965, Ser. No. 514,640 5 Claims. (Cl. 55385) ABSTRACT OF THE DISCLOSURE Domestic automatic dishwasher vent apparatus, for operation during an explosion effect condition, in which a highly porous pad is provided to extend across the vent passage for intercepting and reducing the velocity of the water droplets exiting therethrough during an explosion eifect condition.

This invention relates generally to dishwashing machines and in particular to a vent system therefor.

Domestic dishwashers are usually provided with a vent system which permits limited escape of water vapor and air from the washing chamber during the washing cycle, and which permits circulation of ambient air through the washing chamber during the drying cycle. While the vent systems normally perform their function quite satisfactorily if the machine operates through its full cycle without interruption, under certain conditions of cycle interruption some vent systems serve as a passage through which water droplets are carried and forcibly ejected from the washing chamber. This happens in the following way. If the washing cycle is interrupted with a substantial quantity of hot water in the chamber sump and the machine is then opened (for example, to add an additional dish), the air in the chamber will be relatively cool when the chamber is again closed. Lmmediately restoring the Washing cycle causes a rapid increase in the temperature and static pressure of the air as the still hot water is hurled about the chamber and intimately mixed with the air. The increase in static pressure in the chamber results in the rapid outflow of air and entrained water droplets from the chamber through the vent system. The discharge of water droplets in this fashion is sometimes referred to in the art as an explosion effect, and in the cases of machines having forwardly open vent systems has sometimes resulted in water droplets being discharged with sufficient force as to be thrown five or six feet into the room. Such a condition is of course highly objectionable.

Accordingly, the object of this invention is the provision of a vent system in which the likelihood that water droplets will be thus ejected is substantially reduced.

It is a further object of the invention to provide a solution to the problem which is not inconsistent, in terms of cost, with the relative magnitude of the problem.

I am aware that objectionable discharge of water droplets from some prior dishwashing machines has been prevented by providing a vent system having a sufliciently tortuous or lengthy path, or enough baflles, that the water ejection has been so negligible as to be ignored. However, the provision of such arrangements usually connotes a complexity which I avoid with my invention.

In accordance with my invention, I incorporate my vent system in a water fill housing providing an upwardly directed passage containing a highly porous pad. The pad, during the explosion effect, functions to both filter water from the air, and to reduce the velocity of the water which escapes through the pad. The filtering effect and the energy absorbing effect of the pad are both enhanced by virtue of the substantial cross sectional area of the passage so that the velocity of the air is accordingly reduced. The fill housing has sufiicient height to confine the droplets which get through the pad while they rise to their high point and drop back. Thus the explosion effect is eliminated as a problem of any consequence. Further, a vent system according to the invention is readily adapted for incorporation into the established structural configurations of dishwashing machines of a standard nature without requiring substantial revisions.

The invention will be further described in connection with the accompanying drawing showing a dishwashing machine incorporating the principles of the invention by way of example, and wherein:

FIG. 1 is a side view of an undercounter type dishwashing machine to which the invention is applied, this view omitting some of the structural details which do not bear on the inventive concept;

FIG. 2 is a fragmentary, isometric view of the interior of the dishwasher; and

FIG. 3 is a vertical sectional view corresponding to one taken along the line III-III of FIG. 1.

The dishwasher in FIG. 1 is shown mounted in a cavity below the counter top 10 and has the conventional overall rectangular box-shape defined by a top wall 12, opposite side walls 14, rear wall 16, front wall 18 including an access door portion 20, and a bottom wall 22. The various walls are formed with appropriate embossments for strength and other purposes, but such details of configuration are not illustrated except for the bottom wall sump 24 to which draining water gravitates for recirculation or to be discharged to the drain.

The interior washing chamber of the machine, generally designated 26, is provided with the usual open work racks (not shown) for supporting the articles to be washed. These articles may be inserted from the front of the machine when the access door 20 is open. A pump motor 28, diagrammatically shown in FIG. 1, furnishes power to draw washing and rinsing water from the sump 24 and forcibly hurl it about the washing chamber through means of one or more revolving spray arms 30 (FIG. 2), and to force the used water out to a drain point at the proper time of the cycle. The chamber also contains a resistance heating element 32 adjacent the bottom wall 22 to provide supplemental heat to the wash and rinse water, and to provide the heat for drying the dishes during the drying cycle.

The wash and rinse water is supplied to the washing chamber through a solenoid-valve controlled pipe 34 which empties into a fill housing 36 mounted against the outer face of one of the side walls 14. This fill housing has a generally shallow, rectangular, box-shape formed by outer wall 40, end walls 42 and 44 and horizontal bottom wall 46. The inner edges of the end walls and the bottom wall abut the side wall 14 of the washing chamber in sealed relation to form the upwardly-open pocket or chamber into which Water for washing and rinsing is supplied, and from which it flows into the washing chamber through the horizontal slots 38. As shown, the fill housing has substantial length in a front-to-rear direction along the wall 14, but is of relatively limited height and thickness.

The fill housing, in addition to serving as a plenum, in a sense, through which wash and rinse water are supplied, incorporates a vent system. As such it provides a vertically-extending passage in communication at its lower end with the interior of the Washing chamber through the slot means 38, and in communication at its upper, open, outlet end with the atmosphere exterior of the washing chamber.

As is perhaps best seen in FIG. 3, the fill housing includes a right angle member extending between the opposite end walls with its horizontal leg 48 having one edge abutting the side wall 14 of the washing chamber, and its depending vertical leg 50 spaced inwardly from the outer wall 40 of the housing to provide a passage 52 between the leg 50 and the wall 40. The depending leg 50 may be so located with respect to the slot means 38 that any water discharged horizontally through the slots with any substantial degree of force will strike the depending leg. The leg is also located so that the lower end of the fill housing, in cooperation with the leg, provides a water seal for all practical purposes by accumulating water during the washing and rinsing part of the cycle.

A long strip or pad 54 of highly porous cellular material is secured in the vertical passage 52 to serve as a water and air separator, and as an energy absorber. A preferred material which has been found to give good results is a skeletal (i.e., open cell) structure of polyurethane foam plastic having an average of 10 cells per inch. One manufacturer, the Scott Paper Company, designates its material of this nature as Scott Foam G. Preferably the material is treated with a fire retardant germicidal such as the Du Pont Companys Thiuram. Other materials of a highly porous nature, and having the requisite resistance to deterioration upon exposure to a moist atmosphere may be used in place of the specific material identified above.

In the disclosed embodiment, the forward end of the filter strip 54 stops short of the forward end wall 42 of the fill housing so that the supply pipe 34 may be aimed downwardly into a vertical channel defined between a vertical strip 58 and the end wall 42. The fill water for washing and rinsing purposes is passed through this channel and flows into the washing chamber from the bottom of the housing through the horizontal slot means 38, and one or more bleed holes 56. The strip 58 may conveniently be a length of the same highly porous polyurethane material as the filter pad.

In the operation of the washing device, the hot water is supplied to the washing chamber through the fill housing and slot means 38, and is flung about the interior of the chamber by means of the rotating arm 30. Any water thrown out through the slot means 38 is deflected downwardly by the depending leg 50 of the baflle, accumulates there to serve as a seal, and ultimately drains back into the washing chamber. Any increase in static pressure in the chamber due to the normal washing and rinsing operation is relieved through a small top front vent 60 through which negligible amounts of water in vapor form are carried. The filter pad 54 intercepts any water droplets forced up through the water seal formed in the lower part of the fill housing during washing and rinsing.

The period of heaviest loading of any vent air with entrained water droplets of course occurs when the washing cycle of the machine is interrupted and then restarted with air at room temperature in the washing chamber. In this case the water seal in the lower part of the fill housing has been lost through drainage, and the relatively large venting area thus available accommodates the passage of the water laden air. The filter strip dampens the explosion effect by breaking up the droplets, and captures a part of them while venting the air up through the fill housing vent system passage. Those droplets not captured by the pad have their velocity reduced sufficiently that most of them simply fall back into the fill housing and drain into the tub.

It is noted that the effective area of the pad transverse to the direction of air flow is suflicient that the velocity of air flow therethrough does not exceed a value during the explosion effect that excessive water is carried through the pad.

In alternate embodiments of the invention, the filter strip 54 may be located in the larger cros-sectionalarea of the vertical passage of the fill housing above the deflector baffle. Accordingly the strip may then be of a tighter nature and thus more eflicient without imposing undue resistance to the air flow because the velocity of the air will be reduced in accordance with the increased face area of the strip.

In selecting the filter material, it is important that the resistance of the filter strip and the vent system as a whole be sufficiently low that during the drying cycle operation, air flow may pass through the vent system without undue restriction so as to obtain adequate circulation for drying of the articles in the washing chamber.

While the invention has been described in connection with an undercounter type of dishwashing machine, it is to be understood that it is applicable as well to portable dishwashers having a double-wall construction. The inner walls form the washing chamber and the outer walls providing a finished casing. In this instance the fill housing is well adapted to fit in the space between the double walls by virtue of its relative thinness, and suitable openings are provided in the outer walls adjacent the top of the machine to prevent a buildup of pressure in the space between the double walls during the venting operation.

I claim as my invention:

1. In a domestic dishwashing machine:

means forming an openable washing chamber including a number of vertical walls;

one of said walls including means forming horizontallyextending slot means in the lower portion thereof;

means exterior of said washing chamber forming an upwardly-extending venting passage having its lower end open to said slot means and its upper end open to the atmosphere exterior of said chamber;

a highly porous water and air separating pad disposed in said venting passage to intercept and to reduce the velocity of water in droplet form entrained in the air forcibly expelled through said passage during an explosion effect operating condition of said machine; and

means for conducting said droplets back into said washing chamber.

2. In a domestic dishwashing machine according to claim 1:

said means forming said venting passage includes an upwardly-open vent system housing mounted on the exterior of said one vertical wall, with said slot means being generally aligned horizontally with the lower portion of said housing; and

said housing includes bafile means for deflecting water thrown generally horizontally through said slot means downwardly into the lower portion of said housing.

3. In a domestic dishwashing machine according to claim 2:

said separating pad is disposed between a wall of said bafl le means and a facing exterior wall of said housing.

4. In a domestic dishwashing machine according to claim 3:

said separating pad comprises a highly porous opencell polyurethane material.

5. In a domestic dishwashing machine:

a number of vertical walls, and a top and bottom wall, forming a substantially sealed washing chamber for containing articles to be washed, with at least one of said walls being openable for access to said chamber;

means forming a venting passage extending upwardly along the exterior face of another of said vertical walls, said venting passage having its lower end in communication with the interior space of said chamber and its upper portion having an outlet in communication with the atmosphere exterior of said chamber;

said another vertical Wall of said chamber including means defining an opening in its lower portion serving as an inlet for said venting passage, with the remainder of said another vertical Wall being substantially imperforate; 5

a Water and air separating element in the form of a highly porous pad extending across said venting passage and disposed between said inlet and outlet to intercept and to reduce the velocity of Water droplets entrained in the air forcibly expelled through 10 said passage during an explosion-eflect operating condition of said machine.

References Cited UNITED STATES PATENTS Sway l34*114 Milroy et a1. 1341 14 Duncan 134182 Lentz et al. 55-417 Briggs 55-456 Sinex 55481 Heinicke et al. 134-110 HARRY B. THORNTON, Primary Examiner. B. NOZICK, Assistant Examiner. 

